1. Field of the Invention
This invention relates to an optical mounting system, and in particular to an optical mounting system which allows optical elements of all kinds to be rigidly mounted and yet operated over a wide temperature range.
2. Description of Related Art
In precision optical systems such as interferometers, aberrations caused by strains in the optical materials can have a significant effect on the accuracy of the systems. Principal sources of strains in such systems include temperature-induced strains caused by differences in expansion coefficients between the material of the optical element and the material of the mounting, strains caused by rapid movement of the mounting for focusing and other purposes, or shocks resulting from movements of the device in which the element is housed.
The problem of temperature-induced strains is particularly significant in optical instruments where cryogenic operation is necessary for low signal-to-noise ratio operation, such as for spectral analysis in the infrared range, or which are to be used under extreme temperature conditions such as those found in outer space. While assembly and initial testing of a mounted optical element at cryogenic temperatures can substantially eliminate the problem of temperature-induced strain, such assembly is expensive and impractical, and thus it is conventional to provide a non-rigid mounting which allows for relative expansion and contraction of the optical element and mounting. The non-rigid mounting presents a further problem, however, because mountings which allow free play of the optical element have the disadvantage of allowing momentum to be transmitted to the optical element during rapid movements, causing movement-induced strains. In addition, such epoxy-based joints and spring clips are subject to breakage under conditions such as naval aircraft and spacecraft takeoffs and landings.